Diodes & transistors worksheet with answers

Free printable Diodes & transistors worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
+−Vs​12 VR1​ = 1.5 kΩR2​ = 3.3 kΩID​ = ?

A 12 V DC source is connected through resistor R₁ = 1.5 kΩ to a node X. From node X to the source’s negative terminal there are two parallel paths: resistor R₂ = 3.3 kΩ, and a silicon diode with its anode at X. Use the constant-drop model with 0.7 V. Find the diode current ID in mA.

Vs = 12 VR1 = 1.5 kΩR2 = 3.3 kΩVD = 0.7 V
ID = mA
2.Easy
+−18 V270 Ω5.6 VIR​ = ?

A 5.6 V Zener diode is fed from 18 V through a 270 Ω resistor, with no load connected. Find the current IR in the resistor.

Vin = 18 VVZ = 5.6 VR = 270 Ω
IR = mA
3.Medium
+−15 V100 Ω3.3 V470 ΩIZ​ = ?

A 3.3 V Zener regulator is fed from 15 V through 100 Ω and supplies a 470 Ω load. Find the Zener current IZ.

Vin = 15 VVZ = 3.3 VR = 100 ΩRL = 470 Ω
IZ = mA
4.Medium
RC​ = 1.5 kΩβ = 200RE​ = 1 kΩVCC​ = 20 VR1​ = 56 kΩR2​ = 4.7 kΩ

An NPN transistor with β = 200 has voltage-divider bias from VCC = 20 V: R₁ = 56 kΩ from VCC to the base and R₂ = 4.7 kΩ from the base to ground. The collector resistor is RC = 1.5 kΩ and the emitter resistor is RE = 1 kΩ. Take VBE = 0.7 V and use the Thévenin equivalent of the divider (do not neglect the base current). Find the collector–emitter voltage VCE.

VCC = 20 VR1 = 56 kΩR2 = 4.7 kΩRC = 1.5 kΩRE = 1 kΩβ = 200
VCE = V
5.Hard
+−≥ 24 VR = ?5.6 V≤ 25 mA

A 5.6 V Zener regulator must supply up to 25 mA to a load. The input can drop to 24 V, and the Zener needs at least 2 mA to regulate. Find the largest series resistance Rmax that keeps it regulating.

Vin,min = 24 VVZ = 5.6 VIL,max = 25 mAIZ,min = 2 mA
Rmax = Ω
6.Hard
+−≤ 21 V150 Ω5.6 V

A 5.6 V Zener regulator has a 150 Ω series resistor. The input can rise to 21 V, and the load may be disconnected. Find the largest power PZ,max the Zener must dissipate.

Vin,max = 21 VVZ = 5.6 VR = 150 Ω
PZ,max = mW

Answer key

  1. 1. ID = 7.321 mA
  2. 2. IR = 45.93 mA
  3. 3. IZ = 110 mA
  4. 4. VCE = 17.93 V
  5. 5. Rmax = 681.5 Ω
  6. 6. PZ,max = 574.9 mW

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